An interesting site, that lets you set up a sort of poster board / scrapbook board of the things you like. It can include video, images, text, and music. This means that using it as a class project could be a fun interactive type of learning environment.
This is a really great site for organizing flash card activities. You can do so with particular books, access other instructors files, and create quizzes to correspond with your current class. A very nice site to use for FREE ;-)
Here is a helpful site for working with history, chemistry, or specific writing situations where the frame of reference is time specific. Time lines for all types of events throughout history. Popular Timelines - Timelines.com